System of distribution.



ITO-850,278. v PATENTED APR. 16, 1907.

' L. L. TATUM.

SYSTEM OF DISTRIBUTION. APPLICATION FILED M141, 1906.

INVENTCIH Lewis LTdlvm AT TURNEY n-n: NORRIS PEI'ERS 60., WASHINGTON, n. c.

UNTTED STATES PATENT OFFICE.

LEWIS L. TATUM, OF NORWOOD, OHIO, ASSIGNOR TO ALLIS-CI-IALMERS COMPANY, A CORPORATION OF NEW JERSEY, AND THE BULLOCK ELECTRIC MANUFACTURING COMPANY, A CORPORATION OF OHIO.

SYSTEM OF DISTRIBUTION.

Specification of Letters Patent.

Patented April 16, 1907.

Application filed March 31,1906. Serial No. 309,019.

of Ohio, have invented certain new and useful Improvements in Systems of Distribution, of which the following is a full, clear, and exact specification.

My invention relates to multiple-Voltage systems of distribution having any number of feeder conductors and circuits, and particularly to three-wire systems in which the voltages between the main conductors and the compensating conductor are equal, called the symmetrical three-wire systems, or in which the voltages are unequal, called the unsymmetrical three-wire systems.

It is customary to employ in a multiplevoltage system a balancer, consisting of two or more dynamo-electric machines connected across the main conductors or legs of the system and to the neutral or compensating conductor or conductors. As is well known, when the current-loads on the circuits or branches of the system are equal or balanced the dynamo-electric machines run as motors without load and with slight losses. When the loads are unequal, current flows through one or more compensating conductors and one or more of the machines are driven as generators to supply power to the heavierloaded branch or branches to maintain the voltages at substantially their proper values.

On account of the inherent regulating qualities of compound-wound machines it is desirable to employ compound-wound dynamo-electric machines in the balancer set in order that the generator of the balancer set may supply current at increased voltage as the load on the heavier-loaded branch of the system increases. Since the current through the armature and series field-winding of one of the machines of a balancer when acting as a generator is opposite in direction to that when acting as a motor and since the series and shunt fields of a machine must be cumulative when the machine acts as a generator it follows that the fields are differential when the same machine acts as a motor. In other words, the machines acting as generators have cumulative fields and the machines acting as motors have differential fields and the degree of differential action depends on the value of the current in the compensating conductor, and hence on the difference in the loads on the two sides of the system.

It is well known that a motor having differentially-wound fields may race or run away on current-overload. Heretofore on account of the differential action of the fields of the motor compound-Wound balancers have been unsuccessful when the difference in the loads is considerable, due'to their unstable action and the danger of the machines of the balancer running away. hen the loads are equal and both machines are running as motors, the field. of each machine is due chiefly to the current in its shunt-winding. Now as the loads become unequal the field of the motor due to the current in the shunt-winding is opposed by the field due to the current in the series winding, which is now-greater thanwhen the loads were equal. The result is that the speed of the motor is increased, increasing the voltage of the generator to which it is connected. If the difference in the loads on the two sides of the system becomes greater, the differential field action of the motor increases and its speed becomes correspondingly greater. The result is that the current fed to the lamps or other translating'devices on the heavier-loaded side becomes so great that said translating devices may be destroyed or the balancer may be destroyed on account of its speed.

It has been proposed to employ compoundwound dynamo-electric machines in balancers and to avoid the differential field action of the motor, and hence the danger of the machine running away, by short-circuiting the series winding of either machine when it becomes a motor. While this method is satis- -factory in most respects, it has been found that on account of the low resistance of the series windings and. the rather high contact resistance of the short-circuiting switches that it is a difficult matter to short-circuit or to divert from the motor series winding a sufficient percentage of current to avoid the differential field action. Furthermore, with this methodv it is necessaryto employ shortcircuiting apparatus which are sufficiently sensitive to operate on a very slight unbal-' anced load.

One of the ob ects of my invention is to provide means whereby compound-wound dynamo-electric machines can. be employed in balancers for multiple-voltage systems with less danger of the balancers racing on unbalanced loads.

A further object is to provide means whereby the series winding of the machine acting as a motor when the loads are unbalanced. can be cut out of service at any predeterinined degree of unbalancing, so that the motor acts lirst as a dil'l'erential motor and is then changed to a shunt-motor when the unbalancing reaches a predetermined amount without cruising a sudden. change of voltage, whereby the necessity for the use o'l apparatus sensitive to a slight unbalanced load. is avoided.

A still further object is to improve in general the operation of compound-wouml balancers in nmltiple-voltage systems.

In carrying out my invention 1 provide a balancer which consists of compouml-wound dynamo-electric machines connected to the conductors of the distributing system and provide means for automatically opening the circuit of the series winding of the machine acting as a motor.

More specifically considered, my invention consists in a multiple-voltage system of distribution having one or more balancers consisting of coinpond-wound dynaino-electric machines and means comprising one or more switches and a reverse-current relay for open-circuiting the series field-windings of the machine or machines acting as motors when the unbalanced load reaches a predetermined amount. The field-windings of the balancers are so arranged and connected that after the series windings of the nlotors are opened the motor-arn'iature currents, as well as the generator-armature currents, pass through the series field-windings of the generators. By the dillerential -lield action of the motors of the balancers the speed of the balancers and. the generated voltage are slightly increased, the increase in voltage being about sul'l'icient to compensate for the increase of the internal voltage drop of the machines, and. when the series windings are opencircuited and the motors are changed l'rom dill'erential to shunt motors the speed of the balancers is slightly decreased, but at the same time the currents in the series windings of the generators of the balancers, and hence. the magnetic fields of the generators, are increased to such. an extent as to prevent a decrease in the generated voltage due to a decrease of speed.

My invention still further consists in certain novel combinations and arrangements of parts described in the specification, and set forth in the appended claims.

For a better understanding ol my invention reference is had to the accompanying drawings, in which Figure 1. shows a inultiple-voltage system of distribution in which (JOIUPOUIUl-WOUIHl balancers equipped. with my invention are employed; and .lfiig. 2 shows a system of distribution and a compound-wound balancer, a slightly dil'l'erent apparatus being employed.

lte'l erring now to the figures of the drawings, 10 represents the main source ol' currcntin. this case a gcnerato1' :lor supplying current to the multiple-yoltage system ol' distribution, consisting in this case ol. two main conductors 1]. and 112 and. a neutral or compensating conductor 13%. It may be stated at this point that my invention has equal application to systems in which the voltages between the sets ol. conductors are equal and to those in which the voltages are unequal, or, in other words, to the symmetrical andv the unsymmetrical voltage systems.

My invention. may also be applied to a system in. which there are more than three conductors.

In Fig. 1. two balancers are shown at ll and 15, adapted to operate in parallel to maintain the voltages of the conductors ol' the system at their predetermined values. Each balaneer consists of two compoundwound.dynamo-electric machines 16 and 17. each of which machines consist ol an armature 18, series winding 1%), and shunt-winding 20. The armatures Ofll'ltlfililllOS lb are directly connected to conductor .1] and the arn'iatures ol macl'iines 17 are directly connected to conductor 12. Series windings H) of each balanccr are between the armatures and are connected together in this case by a conductor 21, to which the neutral or com pensating conductor 13% is connected at 22. A low-resistance conductor 23 connects the two machines 16 and 17 of each balancer. In this case the conductors 23 are connected to the machines at the points between the armatures and series field-coils. These two conductors 2?) are joined together by an equalizing-conductor 24;. Located in the conductor 2.]. on both sides ol the point 22. and hence on both sides of the neutral or com' )ensating COTMlllCtUl' 13, are two solenoid open-circuiting switches 25 and 26, As will appear later, the purpose of switch 25 is to cut out ol. service by opencircuiting the series field-windings ol the machines H3 ol the balaneers when the load between conductors 13 and 12 becomes a predetermined amount greater than the load between eonductors ll and lb, 2111(l.tllUllUllUtlOll ol'switch 26 to cut out ol service by open-circuiting the series field-windings ol the machines 17 of the balancers when the load between the cmnluctors ll and 13 becomes a predetermined amount greater than the load between conductors 13 and. 12.

Switch 25 consists ol stationary contacts 27 and a bridgii'ig contact 28, mounted on the lOO ' tion by the springs 39.

core or plunger 29 of the solenoid having a coil 30. Switch 26 consists of stationary contacts 31 and a bridging contact 32, mounted upon the core or plunger 33 of the solenoid. having a coil 34. In this case I. control the solenoid-switches by a reverse-current relay 35. The relay consists of a core 36, having a series winding 37, which is included in the neutral or compensating conductor 13, and a pivoted member carrying potential-coil 38, permanently connected across two conductors of the system, here shown as connected across conductors 13 and 12. The movable element of the relay is held in its mid-position by springs 39 when the loads between the conductors are balanced, the springs being preferably so adjusted that the relay will not be actuated. until the unbalanced load reaches a predetermined amount.

The movable element of the relay carries a contact member 40, adapted to engage when in one extreme position stationary contacts 11 and when in the opposite extreme position stationary contacts 12. As shown in the drawin s, the upper contact of group 1.1 is connected to solenoid-coil 30 of switch and to conductor 11, and the lower contact oi? the group is connected to conductor 12. It is seen, therefore, that when thecontacts 11 are bridged by the contact member 10 of the movable member of the reversecurrent relay coil 30 of switch 25 is energized and the full voltage of the system is impressed upon the coil, which causes a movement of the bridging member 28 away from the stationary contacts 27 and causes the series windings 19 of machines 16 to be open-circuited. When the movable element of the reverse-current relay is actuated in the opposite direction, the group of con-- tacts is bridged by contact member 10 and the full voltage of the system is impressed upon solenoid-coil 3 1 of switch 26, causing switch 26 to be opened and series coils of machines 17 to be open-circuited. It is seen that before contact member 40 bridges the group 12 it leaves group 41, and hence at least one of the solenoid-switches is always closed.

The function and operation of the apparatus will now be more fully explained. When the loads are balanced, the machines of each balancer run as motors without load and with slight losses. Since the series fieldwindings are shunted by the low-resistance conductors 23, little current passes through the series windings and the machines operate as shunt-motors. When the loads between the conductors are equal, no current passes through the compensating conductor 13 to or from the balancers, and hence no current passes through the coil 37 of the reverse-current relay. The movable member of this relay is therefore held in its mid-posi- If new the loads between the conductors become unequal, current flows through the compensating eonductors 13 in one direction or the other and the core of the relay is magnetized. Assume that the load between conductors 11 and 13 is greater than the load between conductors 13 and 12. V tors and machines 17 act motors to supply power to the more heavily loaded side 11 and 13 to maintain the voltages at their predetermined values. Current now flows along the compensating conductor 13, and the coils of the relay are so wound that the torque between. the parts of the relay tend to move the contact member 10 toward the group of contacts 42. The springs 39 are so adjusted that they hold contact member 40 out of engagement with contacts 42 until there is a certain predetermined unbalancing of the loads-for example, until the unbalanced load becomes twenty-live per cent. to fifty per cent. of the greatest unbalanced load for which the apparatus is designed. Until this point of unbalancing is reached current flows along the compensating conductor to point 22, where it divides, passing through both closed solenoid-switches 25 and 26 and through both branches of the conductor 21, through the series field-windings of the motor and generator of each lralancer. Fieldwindings 1.9 and 20 of the generators 16 are now cumulative, and the field-windings 19 and 20 of the motors 17 are now differential. The machines and the apparatus are so designed, however, that the dil'l'erential action is slight and there is no danger of racing. However, if this diflerential action should continue until the unbalanced load becomes excessive the balancers might race and the translating devices, such as lamps or motors, might be destroyed and the machines oi the balancers wrecked. hen the unbalanced load reaches a predetermined amount, the holding Force of the springs 39 is overcome by the torque of the relay, contact member 4-0 is moved into engagement with contacts 12, the circuit is completed from conductor 11 to conductor 12 through coil 34 of the solenoidswitch 26, and the switch is opened. By the opening of this switch the series field-windings 19 of the motors 17 are open-circuited, and hence totally cut out of service. The current necessary to drive the motors 17 now all passes through the upper branch of conductor 21, through the series field-windings of machines 16 of the balancers, and back through conductors 23 to the armatures of motors 17. It is seen that by opening switch 26 the motors are converted from differential to shunt motors. By this operation the fields of the motors are increased and at the same time the fields of the generators are increased. The machines are so designed that the slight increase of speed of the balancers due to the motor differential field Machines 16 now act as generaaction causes a slight increase ol voltage, l il. a single balancer were connected to the which is just sullieient to con'ipensatc lorthe increased internal drop in the machines due totheincrease olloadonthe machines. When the switch 26 is opened and the series lieldwimlmgs are open-circuited, the l'iehlsoi'the motors are suddenly increased, causing a decrease in the speedot the lH'llEUH'OIS. A' Ll/ the same time, however, the 'lields oi the generators are increz'ised, since the 1notor-mirrent, as well as the gelicrater-currcnt, now passes through the series field-windings ot the generators, increasing the generator fields, preot the speed oi the balancers.

hen the load between conductors ii; and 12 is greater than. the load between conductors l1 and 13, machines To act as motors to drive machines 17 as generators to supply power to the more heavily loaded conductors 13 and 12. Current now flows through the compensating comluctor 13 .in the opposite directimi to that when the toad lrctwcen comluctors ]'l and 13 is greater than the load between conductors l3 and 12. l fhen this current reaches a predetermined amount, contact memher liridges crmtacts 4i completing the circuit through the so enoid-coil of switch 25, cutting out ol service the series held-wimlings 1i) oi" machines 16 in the same manner and with the san'ie result previously d cscri bed.

.i t is seen that when the current in conductor 13 becomes sullicient to operate the relay and atter the circuits ot the series windings ot the motors are opened dilleren tial lield actions are entirely avoided. The apparatus can. be adjusted. to operate at any 1u'edetermineil unbalanced. load, it being unnecessary to cut out of service the series 'lield.- windings of the motors when. the loads are slightly unbalanced, tor the reason that the l danger of racing is slight and tor the further reason. that the motors can be changedv l'rom dill'erential to shunt n'iotors at any predetermined. unbalanced load. without causing a sudden change in voltage.

. system are shown. at ll l-'-lventing a drop m voltage due to the decrease \Yhen two or more halancers, each consisli'ng ol two Olll[)l)ll ll(l."\\'()ll ll(l lynanm-electi c machines, are connected andoperated in parallel on the same system, as is shown in Fig. l, the danger to the lamps and. to the machines themselves, due to the dill'erential 'lield action of the motors when the loadsarc excessively un balanced, is greater than when a single balancer isemployed. This is probably due to the fact that the generator ol" one oi the balancers may, in case of an increase or" speed ol that balancer over the other, supply current to the generator oi the latter halancer, changing it to a motor and increasing the speed. of that balancer. Thus the operation. would be very unstable, the function as b lancers would be less, and the danger to the lamps and machines would be greater than.

system. it the series fields of the motors are open-circuitcrl. at a certain predetermineil. unbalancing oi the loads, there is much less danger ot the speed of one balancer becoming greater than the speed. ol' the other balancer. lily invention therefore has a special utility when applied to balanccrs operated in parallel.

in Fig. 2 .l have shown a simplilied. lorm ol' an optm-ciicuiting apparatus. The conductors ol the Illllllll)l('\'l)ltilgtitllfillllJUtill: and. 45. At in is shown a single halancer, which, as in the prccedingcase, consists o'l' two com oun.d-woun. l machines l and. is, each having an armature ll), series lieldavimling Bl), and. shunt 'lieldwinding 5i. '..he armatures are directly connected to conductors -15; and H, respcctiycly, and. the series windings are directly connected. together through a switch. 52, the switchv being located. between the two windings. .s in the precedingcase, a low-resist ance conductor 53 connects a point between the series lield-wimling and the armature o'l one machine to a point betweenv the series 'lield-winding and armature ol. the other machine. The shunt-wilnlings ol the two machines are connected across the conductors 4-23 and 1-4. A single switch. 52 is employed in this case lor cutting out o'l service either series winding, which. switch is i. perated directly by a reversecurrent relay. The switch 52 consists o'l two contact members 5% and 5:3, connected, respectively, to the two series windings, and a bridging member So. This movable contact member so is adapted to be operated. directly by the mowable member o'l' the reverse-current relay. The relay consists ol" a core .37, having one or more series coils 58 included. in the compensating conductor 15, and a movable member 5t), ca rrying a potential coil on, connected across the conductors 4i and 45. The mo able memher so ol the open-circuiting switch 52 is preferably connected directly to the movable member oi the relay and, as shown, is insulal'cd. tiae're'l'rom. As in the preceding case, springs til tend to hold the movable mcmb olihe relay in its central or mid. position. hen the loads are balanced. and no current is passing along the conductor 45, the core is canagnetixed and the movable member o'l the relay is held in its central or mid, position with the bridging contact 5t) ol' the switch in. engagement with bothv stal'ioimry contacts Fri and 55, to which the series coils are connected. it the load between. conductors l2 and becomes greater than. the load l etween conductors 4'5 and, ll, ciu'rent passes along tl 1 1e coruluctor i5 and. macaine t; acts as a motor to drive machine l? as a gcncrator. ii'hcn the loads are only sli htly unbal anccd, the movable member 0 1.: switch still. remains in its central position, and cur- Lil rent passes through the series field-wind ings 50 of both machines, machine 48 acting as a differential motor. Then the unbalanced load reaches a certain amount, determined by the stifl'ness of the springs 61, the pull between the parts of the relay becomes great enough to overcome the resistance of the spring, and the bridging contact 56 of the switch is moved away from the contact 55, so that the connection between the series field-winding 50 of the motor 48 and the compensating conductor 45 is broken. All the current flowing in the compensating conductor now passes through the series fieldwinding 50 of the generator 47, and the motor-armature current passes through conductor 53 to the armature of the motor 48. The motor is now excited solely by the shuntwinding, and generator 47 remains a compound generator having cumulative fields.

I/Vhen the loads again become balanced or the unbalancing falls below the predetermined limit as determined by the tension of the spring, the movable member of the switch is again moved to its central or normal posi tion.

In case the load between conductors 45 and 44 becomes greater than the load between conductors 43 and 45 and the unbalanced load reaches the predetermined amount the switch member is moved away from contact 54 and machine 47 is changed to a shunt-motor, with the same result previously described.

I have shown a reverse-current relay for operating the open-circuiting switches,- but other means can be employed, if desired, for this purpose. If a reverse-current relay is employed, it is not necessary that it be provided with a coil in the compensating conductor, as the desired eflect can be accomplished in many different ways.

I do not desire to be limited to the exact details shown, as many changes can be made without departing from the spirit and scope of my invention.

that I desire to secure by Letters Patent 1s 1.. In a multiple-voltage system of distribution, a balancer comprising compoundwound dynamo-electric machines connected to the conductors of the system, and means for automatically open-circuiting the series field-winding of one of said machines when the loads become unbalanced.

2. In a multiple-voltage system of distri bution, a balancer comprising a plurality of compound-wound dynamo-electric machines connected to conductors of the system, and means responsive to an unbalancing of the loads for-automatically opening the circuit of the series field-winding of any one of said machines.

3. In a multiple-voltage system of distridynamo-electric machines each having series and shunt field-windings, and means responsive to a predetermined flow of current in one of the conductors of the system for open-circuiting the series winding of any one of said machines.

4. In a multiple-voltage system of distribution, main and compensating conductors, a balancer comprising a plurality of dynamoelectric machines each having series and shunt field-windings, and electromagnetically-operated means responsive to a predetermined unbalancing of the loads for open-circuiting the series winding of any one of said machines.

5'. In a multiple-voltage system of distribution, main and compensating conductors, one or more balancers comprising a plurality of compound-wound dynamo-electric machines connected to said conductors, one or more normally closed switches in circuit with the series windings, and automatically-operated means for controlling said switch or switches.

6. In a multiple-voltage system of distribution, a balancer comprising compoundwound dynamo-electric machines, and means comprising a switch for opening the circuit of one of the field-winrilings of one of said. machines when the loads become unbalanced.

7. In a multiple-voltage system of distri bution, a plurality of conductors, a balancer comprising a plurality of compound-wound dynamo-electric machines, and means comprising one or more automatically-operated switches for opening the circuit of either one of the series field-windings when the loads become unbalanced.

8. In a multiple-voltage system of distribution, a plurality of conductors, a balancer comprising a plurality of compoundwound dynamo-electric machines, and means C0111- prising a switch and a reverse-current relay for opening the circuit of either one of the series field-windings upon a predetermined unbalancing of the loads.

9. In a multiple-voltage system of distribution, a plurality of main and compensating conductors, a balancer comprising a plurality of compound-wound dynamo-electric machines, and means comprising a plurality of switches and a reverse-current relay having a coil in a compensating conductor for opencircuiting the series coils of the machines acting as motors when the loads are unbalanced.

10. In a multiple-voltage system of distribution, a plurality of conductors, a plurality of balancers connected in parallel to the conductors of said system, each balancer consisting of compoundwound dynamo-electric machines, and means for open-circuiting the series winding of those machines acting as motors when the loads are unbalanced.

11. In a multiple-voltage system of distri bution, a balancer comprising a plurality of bution, a plurality of conductors, a plurality ol halancers connected in parallel to the conductors of the system, each halancer consisting of two compound-worm(l dynamo-electric machines, and automatic means responsive to a predetermined. nnbalancing ol the loads for open-circuiting the series windings of the machines acting as motors.

12. In a multiple-voltage system of distribution, a halancer comprising compoundwound dynamo-electric machines connected to the conductors ol the system, and means for opcn-circuiting the series winding ot one of said machines when the loads become unbalanced. without opening the armatnrc-circuit of that machine.

, 1.3. In a mult iple-voltage system of distrihution, a halancer comprising compoundwound dynanna-electric machines connected. to the comluctors ol the system, and means responsive to a predetermined unhalancing ot the loads for (.npen'ing the circuit of the series winding of the machine acting as a motor, and means for completing the motor-armature circuit when the series winding is open-circuitml.

14. In. a multiple-voltage system of distribution, a plurality o'li conductors, a halancer comprising two componnd-wmmd dynamoelcctric machines, and automatic means for open-circuiting the series winding of the m achine acting as a motor when the loads are unbalanced, and means comprising an auxiliary conductor for completing the motor-armature circuit when its series winding is open-circuited.

15. In a multiple-voltage system or distrihntion, a plurality of conductors, one or more balancers connected. across the legs of the system, each halancer consisting of a plurality of compound wound dynamoelectric machines, automatically-operating means for opening the circuit of the series winding or windings of the machine or machines acting as motors when the loads are unhalal'iced, and means comprising one or more auxiliary conductors tor completing the motor-circuit of each balancer when its series winding is opcn-circuited.

1.6. In a multiple-voltage system of distribution, a plurality of conductors, a halancer comprising two compouml-wonnd dynamoelectric machines having their armatures connected to the legs ol. the system and the series windings being connected together and. to a compensating conductor between said arma-tnres, a lowresistanee conductor shunting the series windings and means for disconnecting the series winding of either machine from the compensating conductor on a predetermined unhalancing ot the loads.

17. In a multipie-voltage system ol dist rihution, a plurality of conductors, a halancer comprising two compound-wtnunl dynamw electric machines having their armaturcs connected to the legs of the system and the series windings connected directl to each other and to a compensating conductor hetween the armatures, a conductor connect ing a point hetween the armature and series lield-"indiirg ol. one machine to a point oetween the armature and series held-winding ot the other machine,and means comprising one or more switches il or antomatically disconnecting the series held-winding oi" either machine l'rom the compensating conducti'u.

W. In a multiple-voltage system oli distrihution, a plurality of main and compensating conductors, a plurality of halancers connected to said conductors in parallel, each halancer consisting o'l" two compiulnd-woundv dynaino-electric machines having their armatures comiected to the main conductors respectively, and their series windings normally connected, together and to the compensating conductor, means comprising a switch between the compensating conductor and the series windings on each side ot said, compensating conductor 'lor disconnecting the. compensating conductor from the series windings of those machines acting as motors on a predetermined nnhalancing ol the loads, and an auxiliary conductor connected to points between the armatures and series windings of each halancer for conveying the motor-armature current from or to the compensating conductor when the series windings thereot are discom'iectcd 'l'rom the compensating conductor.

In testimony whereof I atl'ix my signature in the presence of two witnesses.

IYitnesses Airmen F. Knvis, Fain) J. Kixsnv. 

